Effects of Rare Earth on Mechanical and Electrical Properties of Copper and Copper Alloys>

The influence of rare earth on the mechanical properties of copper and copper alloys is mainly manifested in hardness, strength, plasticity and so on. When the content of rare earth in pure copper is 0.1% to 0.2%, the strength increases greatly, and when it is higher than 0.2%, the strength increases slowly. The influence of rare earth on the strength of H68 brass has a dual effect: on the one hand, the solid solution strengthening and purification of rare earth increases the strength of the material; on the other hand, when the amount of rare earth added exceeds a certain value, the harmful effect of rare earth is masked.

The effect of rare earth on the conductivity of copper and copper alloys is generally considered to be: on the one hand, the refining effect of rare earth makes copper grains refined, grain boundaries increase, and the probability of electrical scattering increases, This leads to an increase in resistivity and a decrease in conductivity; on the other hand, the purification effect of rare earth reduces impurities in copper, weakens lattice distortion, reduces the probability of electron scattering, and improves conductivity. 

These two factors that have opposite effects on conductivity coexist, and their effects vary with the amount of rare earth added. This theory is in good agreement with the experimental results. For example, the resistivity of Cu2Ni2Si alloy [26] changes with the content of rare earth, which is related to the change of alloy structure caused by the addition of rare earth to Cu2Ni2Si alloy.